7/05 Model HDB2-A Page 4 Rev B
Remove the spool from the sleeve. Using an arbor press or bench vise (with an
improvised mandrel), press the sleeve from the valve body. Take care not to damage
the sleeve. At this point, inspect the o-rings on the sleeve for nicks, tears or abrasions.
Damage of this sort could happen during assembly or servicing. A sheared or cut
o-ring can allow the pump’s compressed air supply to leak or bypass within the air
valve assembly, causing the pump to leak compressed air from the pump air exhaust
or not cycle properly. This is most noticeable at pump dead head or high discharge
pressure conditions. Replace any of these o-rings as required or set up a routine,
preventive maintenance schedule to do so on a regular basis. This practice should
include cleaning the spool and sleeve components with a safety solvent or equivalent,
inspecting for signs of wear or damage, and replacing worn components.
To re-install the sleeve and spool set, lightly lubricate the o-rings on the sleeve with
an o-ring assembly lubricant or lightweight oil (such as 10 wt. air line lubricant). Press
the set into the valve body easily, without shearing the o-rings. Re-install one end cap,
gasket and bumper on the valve body. Using the arbor press or bench vise that was
used in disassembly, press the sleeve back into the valve body. You may have to clean
the surfaces of the valve body where the end caps mount. Material may remain from
the old gasket. Old material not cleaned from this area may cause air leakage after
reassembly. Take care that the bumper stays in place allowing the sleeve to press in
all the way. Re-install the spool, the opposite end cap, gasket and bumper on the valve
body. After inspecting and cleaning the gasket surfaces on the valve body and
intermediate, re-install the valve body on the pump using new gaskets. Tighten the
four hex head capscrews evenly and in an alternating cross pattern.
PILOT VALVE
The pilot valve assembly is accessed by removing the main air distribution valve
body from the pump and lifting the pilot valve body out of the intermediate housing.
Most problems with the pilot valve can be corrected by replacing the o-rings.
Always grease the spool prior to inserting it into the sleeve. If the sleeve is removed
from the body, reinsertion must be at the chamfered side. Grease the o-rings to slide
the sleeve into the valve body. Securely insert the retaining ring around the sleeve.
When reinserting the pilot valve, push both plungers (located inside the intermediate
bracket) out of the path of the pilot valve spool ends to avoid damage.
PILOT VALVE ACTUATOR
Bushings for the pilot valve actuators are threaded into the intermediate bracket
from the outside. The plunger may be removed for inspection or replacement. First
remove the air distribution valve body and the pilot valve body from the pump. The
plungers can be located by looking into the intermediate. It may be necessary to use
a fine piece of wire to pull them out. The bushing can be turned out through the inner
chamber by removing the outer chamber assembly. Replace the bushings if pins have
bent.
TROUBLESHOOTING
PROBLEM: Pump cycles but will not pump. (Note: higher suction lifts require faster
cycling speed for priming.)
POSSIBLE CAUSES:
A. Air leak in suction line.
B. Excessive suction lift.
C. Check valve not closing.
D. Leakage at joint of suction manifold or elbow flange.
E. Suction line plugged.
F. Diaphragm ruptured.
PROBLEM: Pump will not cycle. (Note: Always disconnect air supply to relieve air
pressure before disassembling any portion of pump.)
IMPORTANT
Before pump operation, all external
gasketed fasteners must be inspected
for looseness caused by gasket creep
after leaving the factory. Retorque loose
fasteners to insure against leakage.
Follow recommended torques where
called out. (A card is attached to each
new pump stating this fact.)
This pump is pressurized internally with
air pressure during operation. Always
make certain that all bolting is in good
condition and that all of the correct
bolting is reinstalled during assembly.
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